Aqueous hydraulic cement slurry

ABSTRACT

An aqueous hydraulic cement slurry is provided which has low fluid loss properties at elevated temperatures. In addition to water and a hydraulic cement the hydraulic cement slurry contains a polyamine compound; a lignoamine and/or lignosulfonate; a borate ion releasing compound; and a carbonate and/or bicarbonate.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation-in-part application of Ser. No. 546,845 filedFeb. 3, 1975, now abandoned.

BACKGROUND OF THE INVENTION

Hydraulic cements, i.e., any inorganic cement that hardens or sets underwater, are customarily admixed with water and emplaced as aqueousslurries. The amount of water employed may vary rather extensivelydependent largely upon the fluidity of the slurry required and upon thenecessary ultimate strength. In a great many uses of a hydraulic cementit is necessary for the cement slurry to be emplaced within or next to aporous medium, for example, earthen strata, e.g., in the cementing offof boreholes, grouting, dam and tunnel construction and the like. Whensuch is the case water filters out of the slurry and into the strataduring the setting period. When this occurs to any appreciable extentthere usually results an uncontrolled setting rate, improper placement,impaired strength properties and usually a contamination of thesurrounding strata. All of these undesirable conditions are especiallyto be avoided in cementing operations associated with oil, gas, water orbrine wells. In an effort to lessen the loss of fluid from an aqueoushydraulic cement slurry various materials have been employed. One suchmaterial comprises a polyamine compound selected from the classconsisting of polyalkylenimines, polyalkylenepolyamines and mixturesthereof. A description of these polyamine compounds and their use inhydraulic cement slurries is taught, for example, in U.S. Pat. No.3,491,049, the teachings of which are specifically incorporated hereinby reference. Although these polyamino compounds are quite satisfactoryin environments wherein the temperature of the hydraulic cement slurrydoes not increase to above about 200° F., the fluid loss characteristicsof these cement slurries are unacceptable at higher temperatures.

By practicing the principles of the present invention polyamine compoundfluid loss additives can be made to function in cement slurries atelevated temperatures of 200° F. and higher by also adding to the cementslurry a specific blend of other constituents.

SUMMARY OF THE INVENTION

Hydraulic cement as employed herein is any inorganic cement that hardensor sets under water. Hydraulic cements which can be employed hereininclude, for example, Portland, aluminous and pozzolan cement, includingcements wherein minor amounts of other oxides, e.g., iron oxide, arealso present. Because of its superior strength Portland cements areusually preferred. However, certain advantages are often gained by theuse of other hydraulic cements in admixture with Portland cement. Asemployed herein the term "hydraulic cements" include minor amounts ofextenders such as bentonite, gilsonite and includes such cements usedeither without any appreciable sand or aggregate material (such cementusually being referred to as neat cement) or such cements in admixturewith a granular filling material and/or aggregate, including sand,ground limestone, pebbles and the like. Strength enhancers such assilica flour can also be employed.

The hydraulic cement slurry of the present invention includes inaddition an effective amount of a polyamino compound selected from theclass consisting of polyalkylenimines, polyalkylenepolyamines andmixtures thereof. The cement slurry also includes an effective amount ofa water dispersible lignosulfonate, lignoamine or mixture thereof; aborate ion releasing compound and a carbonate, bicarbonate or mixturethereof. These latter constituents are employed in a weight ratio toeach other and in a total amount which is effective to reduce the lossof fluid from the slurry at an elevated temperature and also to retardthe setting rate of the hydraulic cement slurry at such elevatedtemperatures for a sufficient period of time to permit emplacement ofthe slurry.

DETAILED DESCRIPTION OF THE INVENTION

The operable and preferred ranges of the constituents of the hydrauliccement slurry are set forth in the following Table I:

                  TABLE I                                                         ______________________________________                                                    Operable Range                                                                           Preferred Range                                        ______________________________________                                        Hydraulic cement                                                                              100          100                                              *Water        about 25 to  about 35 to about                                                about 100    75                                                 *Borate ion releasing                                                                       about 0 to   about 1 to about                                                 about 3**    2                                                  *Lignosulfonate, ligno-                                                                     about 1 to   about 1 to about                                    amine or mixture                                                                           about 5      3                                                  *Carbonate, bicarbonate                                                                     about 0 to   about 0.1 to about                                  or mixture   about 3      0.3                                                *Polyamino compound                                                                         about 0.5*** about 0.75*** to                                                 to about 8   about 3                                            ______________________________________                                         *Parts by weight based on 100 parts by weight of the hydraulic cement.        **Maximum about 1 when borate ion releasing compound is a pentaborate, as     hereinafter more fully explained.                                             ***Minimum about 2 when the polyamino compound is predominately               polyalkylene polyamine.                                                  

The polyamine compound employed in the practice of the present inventionshould have an average molecular weight of at least about 1400. Largeraverage molecular weights, however, are preferred, e.g., ranging fromabout 60,000 to 100,000 or even higher. The polyamino compound employedin the practice of the present invention may be prepared according toany one of a number of known procedures. Specific methods for preparingthe polyamino compounds are taught at column 2, line 67 through column4, line 30 of U.S. Pat. No. 3,491,049, these teachings beingspecifically incorporated herein by reference.

The exact amount of each constitutent and ratio of constituents to eachother can vary within a wide range depending on the hydraulic cementemployed. It is well known in this art that the characteristics ofcement may vary even with different lots of the same type of cementobtained from the same supplier. It is not known why various cementscause these differences. Therefore, specific preferred ranges should bedetermined for each batch of hydraulic cement intended to be employed ina cementing operation. Various standardized testing procedures such asthose developed and reported by the American Petroleum Institute undervarious API RP titles can be employed to determine the most preferredparameter for each batch of hydraulic cement.

The lignosulfonates which can be employed in the practice of the presentinvention are selected from the group consisting of alkaline earth metallignosulfonates, alkali metal lignosulfonates, and ammoniumlignosulfonates and mixtures thereof. For example, suitablelignosulfonates are calcium lignosulfonate, magnesium lignosulfonate,barium lignosulfonate, sodium lignosulfonate, potassium lignosulfonateand lithium lignosulfonate. Of these various lignosulfonates, sodiumlignosulfonate, calcium lignosulfonate and mixed salts of calcium sodiumlignosulfonate are preferred because of economy and they have only aminor effect on other desirable cement properties.

The lignoamine constitutent is a main derivative of lignin. In thepulping of woods, such as pine wood, the lignin is subjected to alkalinehydrolysis by sodium hydroxide and sodium sulfite. As a result of thehydrolysis some thio groups are introduced into the lignin molecule inaddition to the formation of a sodium salt of the lignin. The treatedlignin thus obtained may be further treated to induce an alkyl aminegroup in the molecule through a methylene linkage. The amine groups arethe lower alkyl amines having alkyl radicals of up to 4 carbon atoms andmay be primary, secondary or tertiary amines. The product may alsocontain sodium or other metal substituents.

The borate ion releasing compound may be boric acid or a water solubleborate and is preferably employed when it is desired to retard thecement. Of the latter compounds natural minerals such as borax, kerniteand ulexite may be employed. Other water soluble salts such as alkaliand alkaline earth metal borates can also be employed. Specific saltswhich are useful include, for example, LiBO₂ . 8H₂ O; NaBO₂ . 4H₂ O; Li₂B₄ O₇ . H₂ O; Na₂ B₄ O₇ . 10H₂ O; LiB₅ O₈ . 5H₂ O; NaB₅ O₈ . 5H₂ O; KB₅O₈ . 4H₂ O and the like.

As indicated, pentaboric acid salts can be employed in the practice ofthe present invention. Pentaboric acid salts which may be employedinclude alkaline earth metal pentaborates, alkali metal pentaborates andammonium pentaborate. However, care must be taken in use of thepentaborates since it appears that above certain levels they areactually detrimental to the fluid loss properties of the polyaminocompound; alternatively, of course, one may simply employ as the borateion releasing compound, a compound which is not a pentaboric acid salt.The concentration above which the pentaborates become detrimental isgenerally about 1 percent by weight of cement, although the preciseconcentration at which the sharp and easily identifiable objectionablydetrimental effect occurs depends on the particular pentaborate andcement; one skilled in the art can readily determine this concentrationfor a particular pentaborate by a few routine laboratory tests. Forexample, by comparing Tests 24, 25, and 26 in Table II, it can readilybe seen that though the fluid loss at 1% sodium pentaborate was notquite as good as that at 0.5%, the fluid loss at both 0.5 and 1% wasvery satisfactory at less than 100 ml/30 min, whereas a compositioncontaining only a slightly higher amount of sodium pentaborate (1.3%)had virtually no fluid loss control with a blow out occurring so soon asto give a calculated 30 minute fluid loss figure of over 500 ml/30 min.Similarly, Tests 31-36 in Table II show that for potassium pentaborate,the sharp break occurs at between 0.70 and 0.75 percent.

Optionally the hydraulic cement slurry may also contain a water solublecarbonate or bicarbonate. It has been found that the addition of a smallamount of a carbonate, bicarbonate or mixture, generally improves fluidloss control and also permits a reduction in the amount of the polyaminocompound which is necessary. As with the pentaborates, however, highconcentrations may actually be detrimental in some cement systems.Therefore, for each cement system the preferred amount should bedetermined prior to preparation of large quantities of the cementslurry. Examples of bicarbonates and carbonates which can be employedinclude alkali metal carbonates and bicarbonates such as sodiumcarbonate and sodium bicarbonate and the like.

Tests were run in a laboratory to determine the fluid loss properties ofcertain hydraulic cement slurry systems. These tests include bothspecific examples of the present invention and also comparativeexamples. The tests were run according to API RP 10B using a Bariod hightemperature, high pressure fluid loss apparatus and a 325 mesh (U.S.Standard Sieve Series) stainless steel screen. A 500 psi differentialpressure was employed in all tests. In running the tests a hydrauliccement slurry was mixed at room temperature according to the APIprocedure in a Waring Blendor and then heated for 20 minutes in anatmospheric consistiometer at 200° F. The slurry was then transferred tothe preheated fluid loss cell. The cell was sealed under 150 psi andheated to a starting temperature (300° or 350° F. as shown in thefollowing Table II). The test was run by applying 700 psi pressure tothe top of the cell and 200 psi to the bottom through the back pressurereceiver apparatus. The temperature in the cell was allowed to riseduring the test period. Heat was continuously applied to the cell duringthe test so that the final temperature of the hydraulic cement slurry isa function of the length of the test. The figures in the following TableII are for a fluid loss at a test time of 30 minutes or less. The basehydraulic cement slurry to which various constituents were addedconsisted of Lone Star Portland Class H cement containing 35 percent byweight of silica flour and 56 percent by weight of water (bothpercentages are based on the weight of the hydraulic cement). Variousconstituents were also added to various samples of the base hydrauliccement and the fluid loss properties thereof determined. Theconstituents are shown as being added in an amount based on percent byweight of dry cement unless otherwise noted. Table II reports theresults of these fluid loss tests.

                                      TABLE II                                    __________________________________________________________________________    Test                                  Fluid loss                              No.                                                                              PEI                                                                              GH B A LS                                                                              HEC                                                                              SB                                                                              SC                                                                              SNS                                                                              CMHEC                                                                              Pentaborate.sup.(4)                                                                   ml/30 min.                              __________________________________________________________________________     1 .6gls                                                                            -- 2 --                                                                              2 -- 0.1                                                                             --                                                                              -- --   --       46                                      2 .6gls                                                                            -- 2 --                                                                              2 -- --                                                                              0.1                                                                             -- --   --       64                                      3 .6gls                                                                            -- 2 --                                                                              --                                                                              -- 0.1                                                                             --                                                                              -- --   --      None                                     4 .6gls                                                                            -- 2 2 --                                                                              -- 0.1                                                                             --                                                                              -- --   --       80-100                                  5 .6gls                                                                            -- 1 --                                                                              1 -- 0.1                                                                             --                                                                              -- --   --       24                                      6 .6gls                                                                            -- --                                                                              --                                                                              1 -- 0.1                                                                             --                                                                              -- --   --       50/25min.                               7 .6gls                                                                            -- --                                                                              --                                                                              1 -- 0.2                                                                             --                                                                              -- --   --       25                                      8 2% -- 1 --                                                                              2 -- 0.3                                                                             --                                                                              -- --   --       16                                      9 -- 1  --                                                                              --                                                                              --                                                                              0.75                                                                             --                                                                              --                                                                              0.75                                                                             --   --      300                                     10 -- 1  --                                                                              --                                                                              --                                                                              -- --                                                                              --                                                                              1  0.5  --      225                                     11 -- -- 1 --                                                                              2 -- --                                                                              --                                                                              1  0.5  --      500+.sup.(5)                            12 -- -- 1 --                                                                              2 0.75                                                                             --                                                                              --                                                                              0.75                                                                             --   --      500+                                    13 -- -- 1 --                                                                              2 -- --                                                                              --                                                                              -- --   --      500+                                    14 2  -- 1 --                                                                              2 -- 0.3                                                                             --                                                                              -- --   --       34                                     15 -- 1  --                                                                              --                                                                              --                                                                              -- --                                                                              --                                                                              2  --   --      325/4min.                               16 3  -- 1.9                                                                             --                                                                              2.1                                                                             -- --                                                                              --                                                                              -- --   --       14                                     17 0.75                                                                             -- 1 --                                                                              1 -- 0.1                                                                             --                                                                              -- --   --       30                                     18 1.5                                                                              -- 1 --                                                                              1 -- --                                                                              --                                                                              -- --   --      500                                     19 1.5                                                                              -- 1 --                                                                              1 -- 0.1                                                                             --                                                                              -- --   --       42                                     20 1.5                                                                              -- 1 --                                                                              1 -- 0.3                                                                             --                                                                              -- --   --       30                                     21 1.5                                                                              -- --                                                                              --                                                                              1 -- 0.1                                                                             --                                                                              -- --   --      108                                     22 1.5                                                                              -- 4 --                                                                              4 -- 0.3                                                                             --                                                                              -- --   --      500+                                    23 2.25                                                                             -- 3 --                                                                              3 -- --                                                                              --                                                                              -- --   --      140                                     24 2.25                                                                             -- --                                                                              --                                                                              3 -- 0.3                                                                             --                                                                              -- --   Sodium,0.5                                                                             18                                     25 2.25                                                                             -- --                                                                              --                                                                              3 -- 0.3                                                                             --                                                                              -- --   Sodium,1                                                                               60                                     26 2.25                                                                             -- --                                                                              --                                                                              3 -- 0.3                                                                             --                                                                              -- --   Sodium,1.3                                                                            500+                                    27 2  -- 1 --                                                                              2 -- 0.3                                                                             --                                                                              -- --   --       20                                     28.sup.(1)                                                                       2  -- 1 --                                                                              2 -- 0.3                                                                             --                                                                              -- --   --       32                                     29.sup.(2)                                                                       2  -- 1 --                                                                              2 -- 0.3                                                                             --                                                                              -- --   --       75                                     30.sup.(3)                                                                       2  -- 1 --                                                                              2 -- 0.3                                                                             --                                                                              -- --   --      500+                                    31 2.25                                                                             -- --                                                                              --                                                                              3 -- 0.3                                                                             --                                                                              -- --   Potassium,0.50                                                                         38                                     32 2.25                                                                             -- --                                                                              --                                                                              3 -- 0.3                                                                             --                                                                              -- --   Potassium,0.60                                                                         36                                     33 2.25                                                                             -- --                                                                              --                                                                              3 -- 0.3                                                                             --                                                                              -- --   Potassium,0.70                                                                         40                                     34 2.25                                                                             -- --                                                                              --                                                                              3 -- 0.3                                                                             --                                                                              -- --   Potassium,0.75                                                                        500+                                    35 2.25                                                                             -- --                                                                              --                                                                              3 -- 0.3                                                                             --                                                                              -- --   Potassium,0.80                                                                        500+                                    36 2.25                                                                             -- --                                                                              --                                                                              3 -- 0.3                                                                             --                                                                              -- --   Potassium,1.0                                                                         500+                                    37.sup.(6)                                                                       0.75                                                                             -- 1 --                                                                              2 -- 0.3                                                                             --                                                                              -- --   --      500+                                    38.sup.(6)                                                                       1.5                                                                              -- 1 --                                                                              2 -- 0.3                                                                             --                                                                              -- --   --      500+                                    39.sup.(6)                                                                       2.0                                                                              -- 1 --                                                                              2 -- 0.3                                                                             --                                                                              -- --   --      130                                     40.sup.(6)                                                                       2.0                                                                              -- 1 --                                                                              2 -- 0.3                                                                             --                                                                              -- --   --      140                                     41.sup.(6)                                                                       2.5                                                                              -- 1 --                                                                              2 -- 0.3                                                                             --                                                                              -- --   --      110                                     42.sup.(6)                                                                       3.0                                                                              -- 1 --                                                                              2 -- 0.3                                                                             --                                                                              -- --   --       65                                     __________________________________________________________________________     Tests 1-7 and 14-36 were started at 350° F                             Tests 8-13 were started at 300° F                                      PEI is polyethylenimine (Tests 1-27 PEI had molecular weight ranging from     about 40,000 to about 60,000)                                                 In Tests 1-27 an aqueous solution containing about 33 percent by weight o     the PEI described directly above was employed                                 GH is sodium glucoheptonate                                                   B is borax                                                                    LS is lignosulfonate                                                          HEC is hydroxyethyl cellulose                                                 SB is sodium bicarbonate                                                      SC is sodium carbonate                                                        SNS is sodium naphthalene sulfonate                                           CMHEC is carboxymetnyl hydroxyethyl cellulose                                 A is 1:1 by weight mixture of lignoamine and sodium gluocoheptonate           .sup.(1) PSI of 100,000 MW                                                    .sup.(2) PEI of 18,000 MW                                                     .sup.(3) Polyalkylenepolyamine still bottoms. Later reruns of this data a     Runs 39 and 40 suggest there may have been an error in calculating the        active weight of the polyamine compound in Run 30. See also note 6.           .sup.(4) Includes water of hydration                                          .sup.(5) "500+" means the composition had virtually no fluid loss control     with gas blow through occurring in less than a minute                         .sup.(6) Runs 37-42 prepared from 600 g Lone Star H cement, 210 grams         silica flour, 12 grams calcium lignosulfonate, 6 grams borax, 1.8 grams       sodium bicarbonate, and the following quantities of an aqueous commercial     polyalkylenepolyamine product substantially the same as that used in Run      30, but from a different lot. The commercial product contained about 37       weight percent active PAPA and about 13 percent alkali metal halides.         Quantities in the "PEI" column in the table are based on active PAPA.    

    ml. Commercial product                                                                 (sp. gr. 1.14) ml. Additional water                                  __________________________________________________________________________    Run 37   10.7           330                                                   Run 38   21.3           324                                                   Run 39   28.5           320                                                   Run 40   28.5           320                                                   Run 41   35.6           316                                                   Run 42   42.7           312                                               

To cement an 18,000 foot well having a bottom hole circulatingtemperature of 400° F., a bottom hole static temperature of 440° F. anda bottom hole pressure of 20,000 psi the following hydraulic cementslurry can be employed:

Portland cement Class H and, based on the weight of the Portland cement,35 percent of silica sand, 28 percent hematite, 46 percent water; 1.1percent calcium lignosulfonate; 1.1 percent borax; and 0.1 percentsodium bicarbonate, and also 0.5 gallons per sack of Portland cement ofan aqueous dispersion containing about 33 percent by weightpolyethylenimine having a molecular weight ranging from about 40,000 toabout 60,000.

This cement slurry has a thickening time of greater than five hours, afluid loss of 24 cc/30 minutes and develops the following compressivestrengths:

    ______________________________________                                        Temperature                                                                              Time      Compressive Strength psi                                 ______________________________________                                        340° F                                                                            72 hrs.   4550                                                     440° F                                                                            24 hrs.   2720                                                     440° F                                                                            72 hrs.   4165                                                     ______________________________________                                    

To cement a 6,000 foot geothermal well having a bottom hole circulatingtemperature of 450° F., a bottom hole static temperature of about 550°F. and a bottom hole pressure of 3000 psi the following cement slurrycan be employed:

Portland cement Class G containing the following constituents as percentby weight of the dry cement: 35 percent silica sand; 54 percent water;1.2 percent calcium lignosulfonate; 1.2 percent borax; 0.3 percentsodium bicarbonate and 0.5 gallons per sack of dry cement of an aqueousdispersion containing 33 percent by weight of polyethylenimine having amolecular weight ranging from about 40,000 to about 60,000. This cementslurry has the following characteristics:

    ______________________________________                                        Thickening time                                                               3 hours                                                                       Fluid loss                                                                    20 ml/30 minutes                                                              Strengths:                                                                    Temperature   Time     psi                                                    ______________________________________                                               350° F                                                                        48 hours 3000                                                          450° F                                                                        24 hours 1455                                                          550° F                                                                        24 hours 3900                                                   ______________________________________                                    

What is claimed is:
 1. A hydraulic cement slurry composition whichcomprises:(a) hydraulic cement, and the following expressed as parts byweight per 100 parts of said hydraulic cement; (b) water, from about 25to about 100 parts; (c) from about 1 to about 5 parts of a compoundselected from the group consisting of a lignosulfonate, a lignoamine ora mixture thereof; (d) from about 0.5 to about 8 parts of a polyaminecompound having an average molecular weight of at least about 1400,provided that when said polyamine compound is predominately apolyalkylenepolyamine, said range is from about 2 to about 8 parts; and(e) a composition selected from the group consisting of a water solublecarbonate, bicarbonate, or mixture thereof, in an amount from that whichis effective to enhance the fluid loss property of said slurry up toabout 3 parts.
 2. The composition of claim 1 including in addition up toabout 3 parts of a water soluble borate ion releasing compound, providedthat when said borate ion releasing compound is a pentaboric acid salt,said salt is present in an amount of about 1 part or less which is notsharply detrimental to the fluid loss property of the composition. 3.The composition of claim 2 wherein said borate ion releasing compound isboric acid or a water soluble borate.
 4. The composition of claim 1including in addition up to about 3 parts borax.
 5. The composition ofclaim 4 wherein the polyamine is polyethylenimine.
 6. The composition ofclaim 1 including from about 0.1-0.3 parts of a composition selectedfrom the group consisting of a water soluble carbonate, bicarbonate, ofa mixture thereof.
 7. The composition of claim 1 comprising:(a)hydraulic cement, and the following expressed as parts by weight per 100parts of said hydraulic cement: (b) water, from about 35 to about 75parts; (c) from about 1 to about 3 parts of a compound selected from thegroup consisting of a lignosulfonate, a lignoamine, or a mixturethereof; (d) from about 0.75 to about 3 parts of said polyamine compoundprovided that when said polyamine compound is predominately apolyalkylenepolyamine, said range is from about 2 to about 3; (e) fromabout 0.1 to about 0.3 parts of a composition selected from the groupconsisting of a water soluble carbonate, bicarbonate, or mixturethereof; and (f) from about 1 to about 2 parts of a water soluble borateion releasing compound, provided that said borate ion releasing compoundis not a pentaboric acid salt.
 8. The composition of claim 7 whereinsaid polyamine compound is selected from the group consisting of apolyalkylenimine, polyalkylene polyamine or a mixture thereof.
 9. Thecomposition of claim 8 wherein said polyamine compound ispolyethylenimine.
 10. The composition of claim 7 wherein thelignosulfonate is selected from the group consisting of alkaline earthmetal lignosulfonate, alkali metal lignosulfonate, ammoniumlignosulfonate or a mixture of two or more of said lignosulfonates. 11.The composition of claim 7 wherein the lignoamine is a lower alkyllignoamine wherein said alkyl radical contains up to four carbon atoms.12. The composition of claim 7 wherein the borate ion releasing compoundis boric acid or a water soluble borate.
 13. The composition of claim 12wherein the borate ion releasing compound is borax and the polyamine ispolyethylenimine.